Kentaro NAKAMURA Makoto ANDO Naohisa GOTO
A full-wave analysis of antennas with polarization grids is performed. Radiation patterns of antennas for two types of grids (straight strip and curved strip) are presented, where effects of the grid position and the grid paramenters are discussed.
This paper reviews the experimental data that have been reported since 1980 on long-wavelength (λ1µm) optical reflectometry and discusses the different approaches being used. The principles of both the optical time domain reflectometry (OTDR) and the optical frequency domain reflectometry (OFDR) are presented. The experimental data of 35 technical papers mostly on single-mode OTDR which includes optical source wavelength, launching power, length and type of the test fiber, types of the optical source and receiver, etc, are discussed and classified into three categories as: (1) moderate-distance OTDR using a semiconductor laser diode (2) long-distance OTDR using a Nd: YAG laser and (3) coherent OTDR. The principle of the heterodyne-OTDR and its expected advantages over conventional direct-detection-OTDR are also discussed.
Effect of annealing on electrical conductivity of sintered silicon carbide containing boron carbide and carbon was investigated. The silicon carbide was sintered at the temperature range of 1650-2150 for 0.5 hr in vacuum. Samples sintered at above 1980 were annealed in argon at 1750 to 2000 for 0.5 hr to 5 hrs. The electrical conductivity was measured for both non-annealed and annealed silicon carbide, and following results were obtained.(1) The electrical conductivity was reduced about one order of magnitude by annealing for silicon carbide sintered at above 2050.(2) The effect to annealing on electrical conductivity was maximum at 1950 of annealing temperature, and is saturated at 3 hrs of annealing time.
Akira MATSUZAWA Akihiro KANDA Kazuya KIKUCHI Haruyasu YAMADA
A distribution of offset voltage of transistor pairs having fine pattern emitter down to 0.5 µm wide required for a parallel A/D converter can digitize at more than 200 MHz were measured. Moreover, contributions of transistor parameters to offset voltage and a realization of the ultra-high speed A/D converter were discussed. As the result, it was shown that the main transistor parameter contributes to the offset voltages is a fluctuation of a current gain, and a contribution of a emitter contact resistance was not so large. And the realization of 6 bit, 1 GHz or 8 bit, 750 MHz A/D converter was obtained.
Akira MATSUZAWA Yasuto NAKATSUGI Akihiro KANDA Haruyasu YAMADA
In order to realize highly accurate analog to digital conversion for EDTV, HDTV, and video-camera with low power consumption, a monolithic video-rate 8 bit parallel A/D converter has been developed using high-accuracy bipolar transistors with trench isolation. The A/D converter can digitize wide band video signals up to 10 MHz with high signal to nose ratio (45 dB at 10 MHz input) at high conversion rate of 40 MHz. Notwithstanding it contains 7000 bipolar transistors, it consumes only 250 mW and is formed with small chip size (2.73.9mm2).
Naoyuki SHIGYO Koichi SATO Koichi KATO Tetsunori WADA
This letter describes the newly developed device simulator TRITON. Emphasis is on the fully automatic triangle mesh generation, based on the string data which represent the device shape. Poisson's and current continuity equations for electrons and holes are discretized by the control volume method.
Hiroshi KONDO Yoshiaki NAGANO Kazunobu KANDA
We derive the relationship between the Fourier transform magnitude and the phase of the original signal from the degraded one. The phase of the original signal can then be specified uniquely from the Fourier transform magnitudes of the relevant signals and the phase of the degraded signal and the system transfer function.
Yasuyuki KATO Toshio OOYANAGI Akihiko ISHIKURA Mitsuru MIYAUCHI
A new stuffing-pulling fusion technique for the mass fusion splicing of single-mode fibers is presented, where the fiber spliced-region is pulled after the fiber end faces are fused and stuffed to each other. The characteristic feature of this technique is that the stuffing and pulling strokes are varied, based on the observation of fiber end face gaps for every splice. This technique can reduce splice loss to a half in comparison with the conventional method.
Hiroo UKITA Yoshitada KATAGIRI
The light output of a injection laser in a short (several µm) external cavity has been investigated both experimentally and theoretically. The amplitude modulation ratio of the light output signal reaches maximum where the drive current is below the threshold lasing current. An antireflection coated (ARC) laser diode is useful in increasing the light signal.
A Burmese English word Processing System (BEPS) has been designed as a prototype system for development on a pernonal computer. BEPS can process visually natural output letters and has advanced capabilities comparable to those of modern English word processing systems.
Masahiro MURAGUCHI Kuniki OHWADA
A Ku-band monolithic voltage controlled oscillator (VCO) has been developed. All the circuit elements for the VCO, i.e., an FET, a control diode, an output matching circuit, a stabilizer, and associated circuitary were integrated on a single chip. This VCO is characterized by using a unique stabilizer. The VCO with its stabilizer has shown stable oscillations across a tuning bandwidth covering 12.30 to 12.80 GHz with control voltage of 1 to 3.5 V. The output terminal of the chip can be directly connected to 50 ohm loads and requires no additional attenuator or isolator to stabilize it.
Yoshihisa SAKAI Shigeki AISAWA Ken-ichi HAYASHI Kazuo ARAI Yoshio IDA
The influence of 1/f noise in FM noise on the spectral linewidth of semiconductor lasers in a normal operation has been investigated. The linewidth calculated from the FM noise spectrum considering the 1/f noise agrees with that obtained from the delayed self-heterodyne method.
Kenji MOCHIZUKI Isamu SATO Ryoichi ARAI
This letter describes a highly sensitive method for detecting contact between a head slider and disk medium. It is shown to provide 10 dB or greater improvement in the signal to noise ratio (SNR) from the small piezoelectric transducer attached to the head slider by using a new frequency mixer circuit.
Masayuki KAWAMATA Tatsuo HIGUCHI
In order to suppress constant input limit cycles in 2-D separable denominator digital filters, bias cancel realizations are proposed by modifying 2-D separable denominator digital filters free of zero imput limit cycles.
Nobuo KUWABARA Tsuyoshi IDEGUCHI
An analytic expression of electromagnetic near field emitterd by a single current flow along a straight wire is derived to obtain the radiated EMI limit from the telecommunication lines connected to the equipment. The validity of the theory is tested in the experiment. Calculations show that the conversion factor between the electric field strength and the terminal voltage is not significantly changed by the wire length. A maximum conversion factor of about -30 dB in the frequency range of 0.1 -30 MHz is obtained.
Toshiyuki KANO Hiroshi TANIGUCHI Hiroshi SAITO
A copper vapor laser performance by using a metal-vapor-complex reaction (CuAlBr3) is reported. The laser operation is obtained at a low temperature without external heating because of the AlBr3 vapors evaporation at a room temperature. The copper vapor laser using this metal-vapor-complex reaction has an advantage of deposition-free of a metalilc copper to the laser tube wall, which is different from the copper halide and the organometallic copper lasers.
Fumihiko ITO Tadatoshi TANIFUJI
A design principle of total reflection type optical switches with broad wavelength bandwidth using the plasma dispersion effect in GaAs is described. Wavelength dependent excess loss due to Goos-Hanchen shift in wavelength region from 1.3µm to 1.55 µm is reduced to within 0.1 dB with waveguide cross angle of 5 and injected current density of 16 kA/cm2.
Fumio UENO Takahiro INOUE Yuji SHIRAI Mamoru SASAKI
A maximum and a minimum circuits with multiple inputs are proposed. The operating speeds of these circuits are independent of the number of the inputs. Since the proposed circuits consist of only NMOS transistors, they can be implemented in semi-custom IC forms. A potential application of these circuits is a real-time fuzzy controller.
Tanroku MIYOSHI Hiroshi KIMURA Matsuto OGAWA
As a general approach to analyse the field effects on a quantum well with arbitrary potential distribution, a method based upon finite element is presented. The field dependence of the resonant width and the effective energy gap is analysed for quantum wells with potential deformation around the center of wells.
Toshiyuki TANAKA Kiyotoshi YASUMOTO
A two-dimensional radiation by a relativistic sheet electron beam passing over a corrugated conducting surface is investigated. The leakage coeffcient and phase change of space-charge waves due to the radiation is calculated using a perturbation approach based on the multiple scales.